1. Field of the Invention
The present invention relates to a semiconductor device having a pixel electrode, especially a display device.
2. Description of the Related Art
In manufacturing an active matrix display device, in general, a wiring to be connected to a semiconductor film of a thin film transistor (TFT) is formed and a conductive film to be a pixel electrode is formed over the wiring. Therefore, a resist mask for forming the wiring and a resist mask for forming the pixel electrode have been required.
Further, as another example, an example is given, in which a conductive film to be connected to a semiconductor film of a TFT is formed, the conductive film is made to serve also as a pixel electrode, and a metal film is formed over the conductive film (for example, Patent Document 1: Japanese Published Patent Application No. Hei6-230425). This example is different from the example described above. A transparent conductive film is employed as the conductive film, and the transparent conductive film is directly connected to the semiconductor film. The transparent conductive film is formed from a material having high resistance in many cases; therefore, in order to cover high electric resistance of the transparent conductive film, the metal film is formed over the transparent conductive film.
Also in Patent Document 1, in which the transparent conductive film is directly connected to the semiconductor film, a resist mask for forming a pixel electrode by etching the transparent conductive film and a resist mask for etching the metal film have been required.
In a conventional active matrix display device, a resist mask has been required for each layer in forming a stacked wiring. In particular, there are a number of stacked structures in forming a pixel electrode, and at least a resist mask for forming the pixel electrode and a resist mask for etching a film to be stacked over the pixel electrode are required. Thus, there have been a number of manufacturing steps. Therefore, a manufacturing cost of a semiconductor device like a display device has not been lowered.